1. The Field of the Invention
The invention is directed to a system for dispensing a liquid. More specifically, the present invention is directed to a liquid dispensing system for dispensing a precise quantity of a liquid.
2. Present State of the Art
Many manufacturing processes require the use of precise quantities of liquids. To produce consistent products, it is important that precise quantities of liquids be consistently and repeatedly dispensed. For instance, in photolithography, to produce a photoresist film that is sensitive within 50 .ANG., a precise quantity of chemicals must be dispensed. Even a slight deviation in the quantity of a chemical can taint the photoresist film and the photolithography process.
The precise dispensing of chemicals is dependent on numerous factors, such as flow rate and the manner in which the chemical is dispensed. The flow rate and the manner in which liquids are dispensed is primarily dependent on the system used to dispense the liquid. For instance, to repeatedly dispense a precise quantity of a liquid, the dispensing system needs to be a precise instrument, having a precise conduit to dispense the liquid, and a precise dispensing site to prevent dripping after dispensing is complete. Furthermore, it is important to have a fluid tight system that provides a smooth flow of liquid without leakage or other fluid disturbance. It is also important that the system have a constant dispensing position, such as a constant angle of dispensing and constant dispensing distance, so that a consistent dispensed quantity of liquid is reliably repeated.
Conventional dispensing systems are composed of numerous intricate parts which increase the chance of leaks and the chance of an inconsistent dispensing position. For instance, a typical dispensing system has at least a nozzle portion composed of a rigid tube connected to a flexible tube that feeds liquid to the nozzle portion. The rigid tube is connected to the flexible tube in a conventional nut and bolt relationship. The rigid tube is joined to a steel tubing with a second nut and a nozzle is connected to the steel tubing by a third nut. Liquid is fed to the nozzle portion via the flexible tube, through the rigid tube, the steel tube, and into the nozzle where the liquid is dispensed.
The numerous parts making up conventional dispensing systems require numerous connections which increase the chance of errors. Typically, after repeated use, these conventional dispensing systems develop openings at the connections causing leaks and allowing air into the system. Air in the dispensing system disturbs the flow of the liquids causing a fluctuation in pressures, referred to as turbulence, and results in irregular dispensing.
Another problem is that conventional dispensing systems are typically not adaptable to different liquid storage assemblies and do not have a means of stabilizing the flexible feeding tube which delivers the liquid to the dispensing system. Hence, conventional dispensing system must be changed each time the liquid storage assembly is changed. It is difficult to maintain a consistent dispensing position when the dispensing system is constantly being changed. In precise dispensing processes, even the slight deviation in distance or angle of dispensing can adversely effect the precise nature of the dispensed liquid.
In view of the drawbacks to the presently used systems for dispensing liquids, it is readily apparent that there exists the need for a dispensing system that consistently dispenses precise quantities of liquids. In addition, there is a need for a simple, adaptable dispensing system that can be quickly and easily adapted and modified to attach to a wide variety of liquid dispensers so that the dispensing position remains constant.